Btw, any insight on the strange nature pf the noise described in the previous posts ? ... Im curious ... am i being contacted by alien life forms ? ;-)
Resistence is futile!

These were my thoughts when I read your first post:

( BTW, full screen video, etc. could cause the hard drive to be accessed more frequently, hence the noise being more prevalent . )

The hard drive has an electrical motor in it.
I asked if they were re-positioned when you moved them.
Moving them ( say flat, then on the side ) can put strain on different portions of the drive such as bearings. Especially as in the case of a hard drive going bad, worn bearings etc., where the platters can tilt ever-so-slightly, or something loose inside can rub against something, can cause electrical interference and can be picked up by other devices. The repositioning can alter the amount of stress ( thus noise ) which causes the interference.

The interference is going to be most prominent in the electrical circuit of the hard drive, but, if the device is using, lets say, the EIDE interface as partial ground for the motor instead of a separate ground to earth, those noises can also be picked up by anything also connected to that interface. ( and don't forget the motherboard components doing the same thing if it is not properly grounded to chassis. )

Ever wire a car stereo?
Years ago, ( probably long before your time ) cars used to use the car chassis for the neg. ground on the speaker, and have just a single positive wire to the speaker. The speakers would pick up noises from other parts of the car. When someone was installing a high-end system they would always have to run their own wires with both positive and negative strands to eliminate these noises, usually a much thicker gauge wire then original to provide less resistence so the current would travel the new wires' path rather then seek a noisier one ( and handle the greater power outputs, but that is another topic. )

As electricity will travel the path of least resistence, maybe resistence is not futile!

( I have not studied electronics in over 30 years and as its relevance to this situation is of less importance I am not going to get into a discussion of a computer case as a faraday cage. I'll leave that to others! )

Hope this made sense.